Voltage regulators, such as DC to DC converters, are used to provide stable voltage sources for electronic systems. Switching voltage regulators are known to be an efficient type of DC to DC converter. Such voltage regulators typically include a power switch to generate a rectangular-wave voltage that is then filtered to provide the output DC voltage.
Conventionally, a power switch was fabricated on an integrated circuit chip with wire bond packaging. More recently, the power switch has been fabricated as an integrated circuit chip with flip-chip packaging.
Conductive pads are formed on at least one surface of the chip to provide electrical couplings to the integrated circuit components, e.g., transistors, internal to the chip. Traditionally, the electrical coupling between the transistors and the conductive pads is accomplished through the use of multiple conductive routing layers that are formed over the semiconducting substrate of the integrated circuit chip but below an insulative layer that supports the conductive pads and separates the pads from the routing layers (an aperture in the insulative layer can provide electrical coupling of the contact pad to the uppermost conductive routing layer). For example, an integrated circuit chip may have metal lines and vias that electrically couple the source and drain regions of the transistors to the conducting pads of the integrated circuit chip.